I am a bit dissapointed that there is no new filesystem, but all the power saving and optimization features are simply incredibly amazing. If it really works that smoothly, then this is indeed some ingenious software engineering and a much bigger deal then most people would think. For example, something like timer coalescing Craig talked about is really difficult to implement. The multiple display support is also a big deal and much harder to do properly then some might think.
And they seems to have solved almost everything people complain about in ML I am happy that Apple seems to focus at technical, innovative aspects of software again and not just looks.
I was right about Final Cut X. As much of a problem as people had with it, it was clearly a prototype of where Apple is headed. Those of us who took the time to learn FCX are familiar with tags already. Glad to see it spreading.